As for a conventional refrigerant compressor of this type, the development of a high-efficiency refrigerant compressor which consumes less quantity of fossil fuel has been promoted from the viewpoint of global environment protection. Particularly, special efforts are made to lower the lubricant viscosity and to decrease the sliding loss. Such a conventional refrigerant compressor is, for example, disclosed in Japanese Patent Laid-open Application No. 2000-297753 and Japanese Patent Laid-open Application No. H10-204458.
A conventional rotary compressor will be described in the following with reference to the drawings.
FIG. 14 is a sectional view of a closed type electric refrigerant compressor based on prior art. FIG. 15 is an enlarged view of portion E of the prior art. Hermetic container 1 stores oil 2 that is mineral oil ranging from VG15 to VG20 in viscosity, which also accommodates electric motor 5 that is a motor element formed of stator 3 and rotor 4, and reciprocating compression mechanism 6 driven by the motor. Also, the refrigerant used is R600a.
Next, the detail of compression mechanism 6 is described in the following.
Crank shaft 7 comprises main shaft 8 with rotor 4 press-fitted therein and eccentric member 9 formed eccentrically of main shaft 8, which is furnished with oil feeding pump 10. Cylinder block 11 includes compression chamber 13 formed of generally cylindrical bore 12, and bearing 14 which supports main shaft 8.
Piston 15 movably fitted in bore 12 is connected to eccentric member 9 via piston pin 16 by means of a connecting means, connecting rod 17.
Valve plate 20 is disposed so as to seal the end of bore 12, thereby forming suction hole 24 and discharge hole 25. Suction reed 18 formed from plate-spring material is held between the end of bore 12 and valve plate 20, and serves to open and close the suction hole. Discharge reed 19 formed from plate-spring material is disposed at the opposite to bore 12 side of valve plate 20, and serves to open and close the discharge hole. Head 21 is fixed at the opposite to bore 12 side of valve plate 20, thereby forming high pressure chamber 26 which accommodates discharge reed 19.
Suction tube 22 is fixed on hermetic container 1 and is connected to the low pressure side (not shown) of the refrigeration cycle, which leads the refrigerant (not shown) into hermetic container 1. Suction muffler 23 is held between valve plate 20 and head 21.
Sliding surfaces are respectively formed between main shaft 8 of crank shaft 7 and bearing 14, between piston 15 and bore 12, between piston pin 16 and connecting rod 17, between eccentric member 9 of crank shaft 7 and connecting rod 17.
A series of operations in the configuration above mentioned will be described in the following.
The power supplied from a commercial power source (not shown) is supplied to electric motor 5, which rotates rotor 4 of electric motor 5. Rotor 4 rotates crank shaft 7, and the eccentric motion of eccentric member 9 is transmitted from the connecting means, connecting rod 17, to drive the piston 15 via piston pin 16, and thereby, piston 15 reciprocates in bore 12.
And, the refrigerant gas led into hermetic container 1 through suction tube 22 opens the suction reed 18 via suction muffler 23 and is sucked up into compression chamber 13 from suction hole 24. The refrigerant gas taken into compression chamber 13 is continuously compressed, and opens the discharge reed 19 and is discharged from discharge hole 25 into high pressure chamber 26, which is then delivered to the high pressure side (not shown) of the refrigeration cycle.
Oil 2 is fed from oil feeding pump 10 to each sliding surface as crank shaft 7 is rotated, lubricating the sliding surfaces and decreasing the friction coefficient, and also serves the function as a seal between piston 15 and bore 12.
Also, in order to suppress the deposition of PET (polyethylene terephthalate) or the like contained in oil 2, the boiling point component at 400° C. or over of oil 2 is 20% or over in volume ratio.